The present disclosure relates to a display panel provided with an organic EL (electroluminescent) device, and to a display device and an electronic instrument provided with the display panel.
In recent years, in the field of display devices carrying out image display, current driven optical devices having light emission brightness changed in accordance with a flowing current value, for example, display devices using an organic EL device are developed as a light emitting device for a pixel to pursue commercialization (for example, refer to Japanese Unexamined Patent Application Publication No. 2008-083272). An organic EL device is a self light emitting device, different from a liquid crystal device and the like. Therefore, since a display device using an organic EL device (organic EL display device) does not seek a light source (back light), the visibility of an image is high, the power consumption is low, and also the response speed of a device is fast compared with a liquid crystal display device seeking a light source.
In organic EL display devices, similar to liquid crystal display devices, there are a simple (passive) matrix system and an active matrix system as a driving system thereof. While the passive matrix system has a simple structure, it has problems such that it is difficult to realize a display device of large scale and high resolution. Therefore, currently, development of the active matrix system is carried out extensively. This system controls a current flowing in a light emitting device disposed for each pixel with an active device (TFT (thin film transistor) in general) equipped in a driving circuit equipped for each light emitting device.
FIG. 15 represents a schematic configuration of a general organic EL display panel. A display panel 100 illustrated in FIG. 15 is provided with a display region 100A with a plurality of display pixels 120 two dimensionally arranged therein.
Each display pixel 120 is configured to include a subpixel 120R for a red color, a subpixel 120G for a green color, and a subpixel 120B for a blue color. The subpixels 120R, 120G, and 120B are configured with, as shown in FIG. 16, organic EL devices 121R, 121G, and 121B and a pixel circuit 122 connected thereto. FIG. 16 represents a circuit configuration of the subpixels 120R, 120G, and 120B. Hereinafter, a subpixel 120 is used as a generic name of the subpixels 120R, 120G, and 120B. In addition, an organic EL device 121 is used as a generic name of the organic EL devices 121R, 121G, and 121B.
The pixel circuit 122 is configured with a writing transistor Tws, a retention capacitor Cs, and a driving transistor Tdr and has a circuit configuration of 2Tr1C. A gate line WSL is formed to extend in a row direction and is connected to a gate 123A of the writing transistor Tws. A drain line DSL is also formed to extend in a row direction and is connected to a drain 124C of the driving transistor Tdr. A signal line DTL is formed to extend in a column direction and is connected to a drain 123C of the writing transistor Tws. A source 123B of the writing transistor Tws is connected to a gate 124A of the driving transistor Tdr and one end (terminal 125A) of the retention capacitor Cs. A source 124B of the driving transistor Tdr and the other end (terminal 125B) of the retention capacitor Cs are connected to an anode 127A of the organic EL device 121. A cathode 127B of the organic EL device 121 is connected to an external cathode line CTL.